Innovations in house building

26. Februar

We all want to have somewhere to live. But our dwellings are anything but environmentally friendly. 50 percent of the energy produced and the resources mined worldwide are used in the construction and operation of buildings. 40 percent of global CO2 emissions and about half of all waste are attributable to the construction industry. This is why researchers are experimenting with innovative materials to make house building more climate-friendly. We present four interesting approaches.

How would it be if we could print houses instead of building them? 3D printers offer the potential for houses to be built faster and perhaps even more cheaply than conventional techniques. The first buildings to come from a printer have already been inaugurated in Germany, including a Data Center in Heidelberg. But the technology is still in its infancy and uses conventional concrete as a building material. Cement is the binder used in concrete – and it’s responsible for around eight percent of global CO2 emissions.

Researchers in the USA have developed a climate-friendly alternative. According to the team at Oregon State University, whereas the concrete normally used in 3D printing is made up 30 to 60 percent of the type of cement that is harmful to the climate, the new building material consists of 70 to 80 percent organically based material. The main ingredient is clay mixed with hemp fibres, sand and biochar.

The materials can be extracted locally, which further reduces their climate impact. And where cement-based concrete takes 28 days to harden, the clay-based alternative is firmly set and load-bearing after just three days. This means that it could be used to quickly build new accommodation after earthquakes and other natural disasters. And, more generally, it could help to meet the housing needs of the growing world population. Before that happens, however, the new material still has to be thoroughly tested, and the costs compared to conventional concrete need to come down.

While hemp is one material among others in the sustainable concrete substitute developed by the US researchers, in other contexts the traditional and multifunctional natural fibre is the main ingredient. Companies in Germany, France and the Italian autonomous province of South Tyrol are producing insulation boards and blocks from hemp. The latter consist of a blend of hemp fibres and lime and are produced for installation in a timber frame or reinforced concrete skeleton.

Hemp blocks and slabs offer a whole range of advantages. The first of these is their very good level of thermal insulation: They keep the heat in in winter and out in summer. They are also sound-absorbing, mould- and  fire resistant and moisture-regulating. Like clay, therefore, they ensure a healthy indoor atmosphere. And what is positive for the global climate is the fact that the unfussy and fast-growing hemp plants have a negative CO2 balance. This means that they bind more carbon dioxide than is released during cultivation and production. And while conventional insulation materials such as polystyrene or mineral wool sometimes have to be disposed of as hazardous waste during demolition or conversion, the hemp blocks can be easily composted or crushed into raw material to make new blocks.

It is true that the construction costs for a house made of hemp are currently still around ten percent higher than they would be for a conventional house made of concrete. However, over its entire service life it should make up for this cost disadvantage. In South Africa, a high-rise building made of hemp has already been erected. This rediscovered natural fibre is also being used as a building material in Canada, Switzerland and France. The French are the largest producers of industrial hemp in the EU – well ahead of Germany and the Netherlands. In Germany, hemp houses can be found in places such as Rügen and in the Swabian Alb. They have been built by Henrik Pauly, who has made a name for himself as Germany’s first hemp engineer.

Houses usually outlive multiple generations of inhabitants. However, this is by no means true for all of their components, especially those found inside them: Wooden cladding, stud walls, floors, pipes and cables must be repeatedly replaced throughout the life of a building. This takes time, energy and resources. And since these are mostly composites, they are often difficult to recycle. But what if short-lived structures could be combined with durable retaining walls and easily removed and replaced – by using Velcro as a fastener, for instance? This is exactly the idea that a team from the Technical University of Graz is working on in its ReCon project. “The central principle of ReCon is to use clearly defined and separable interfaces to make it easy to dismantle buildings,” says project manager Matthias Lang-Raudaschl from the Institute of Architectural Technology. “This will prevent a lot of construction waste and material consumption.”

The Velcro concrete system developed by the researchers works just like the little fasteners that hold our shoes, backpacks or jacket sleeves together – only on a much larger scale. At the ends of the long-lasting components are mushroom-shaped structures. Elastic loop elements attached to the short-lived structures can be hooked into these and unhooked again as and when required. Initial tests in the laboratory were promising: All the Velcro elements developed in the project demonstrated an adhesive tensile strength comparable to industrial products. However, it will probably be a while before we will actually be able to attach and detach ceilings and walls. Methods must first be developed for the industrial scale production of this sustainable fastening system for building components.

The TRIQBRIQ start-up is already a few steps ahead in this respect. With their climate-friendly and recyclable wooden building blocks, the Tübingen-based company has won various sustainability awards and even been featured in the “Sendung mit der Maus”, Germany’s long-established educational programme for children. The modules are called Briqs and are reminiscent of vastly outsized wooden Lego bricks. They are made of the used wood that piles up during demolition or renovation work. Weak and damaged wood is likewise used in their production. The former is so called because the diameter of the original trunk is insufficient for use in furniture or the like. The latter is wood which has been killed off by pests such as the bark beetle, which is affecting more and more spruce trees in northern latitudes in this age of climate change. While these types of wood have previously mostly had to be burned, they can now be used to make Briqs without any loss of quality, meaning that the CO2 bound in them can be stored permanently. The wood is processed in regional sawmills, which further reduces the CO2 footprint of the modules.

On the construction site, the Briqs are then put together like Lego bricks and locked in place with wooden dowels. Because this is much faster – it takes less time than erecting a wall made of stone or concrete – the technique should be able to hold its own against conventional construction methods in terms of price. And because the Briqs do not require any glue, they can easily be reused or dismantled into their components during conversion or demolition work.

Several single-family houses have already been built using these breathable building blocks, alongside a three-storey apartment building in Tübingen which provides accommodation for homeless people. Braunschweig has been home to the world’s frst supermarket made of wooden blocks since May 2025. Construction work is currently underway in the Berlin district of Spandau: Here, a temporary district centre is being created from these sustainable building blocks which is scheduled for opening at the end of March.